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/*
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 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
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package java.time.temporal;

import java.time.DateTimeException;
import java.util.Objects;

/**
 * Framework-level interface defining read-only access to a temporal object,
 * such as a date, time, offset or some combination of these.
 * <p>
 * This is the base interface type for date, time and offset objects.
 * It is implemented by those classes that can provide information
 * as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}.
 * <p>
 * Most date and time information can be represented as a number.
 * These are modeled using {@code TemporalField} with the number held using
 * a {@code long} to handle large values. Year, month and day-of-month are
 * simple examples of fields, but they also include instant and offsets.
 * See {@link ChronoField} for the standard set of fields.
 * <p>
 * Two pieces of date/time information cannot be represented by numbers,
 * the {@linkplain java.time.chrono.Chronology chronology} and the
 * {@linkplain java.time.ZoneId time-zone}.
 * These can be accessed via {@linkplain #query(TemporalQuery) queries} using
 * the static methods defined on {@link TemporalQuery}.
 * <p>
 * A sub-interface, {@link Temporal}, extends this definition to one that also
 * supports adjustment and manipulation on more complete temporal objects.
 * <p>
 * This interface is a framework-level interface that should not be widely
 * used in application code. Instead, applications should create and pass
 * around instances of concrete types, such as {@code LocalDate}.
 * There are many reasons for this, part of which is that implementations
 * of this interface may be in calendar systems other than ISO.
 * See {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues.
 *
 * @implSpec This interface places no restrictions on the mutability of implementations, however
 * immutability is strongly recommended.
 * @since 1.8
 */
public interface TemporalAccessor {

  /**
   * Checks if the specified field is supported. <p> This checks if the date-time can be queried for
   * the specified field. If false, then calling the {@link #range(TemporalField) range} and {@link
   * #get(TemporalField) get} methods will throw an exception.
   *
   * @param field the field to check, null returns false
   * @return true if this date-time can be queried for the field, false if not
   * @implSpec Implementations must check and handle all fields defined in {@link ChronoField}. If
   * the field is supported, then true must be returned, otherwise false must be returned. <p> If
   * the field is not a {@code ChronoField}, then the result of this method is obtained by invoking
   * {@code TemporalField.isSupportedBy(TemporalAccessor)} passing {@code this} as the argument. <p>
   * Implementations must ensure that no observable state is altered when this read-only method is
   * invoked.
   */
  boolean isSupported(TemporalField field);

  /**
   * Gets the range of valid values for the specified field.
   * <p>
   * All fields can be expressed as a {@code long} integer.
   * This method returns an object that describes the valid range for that value.
   * The value of this temporal object is used to enhance the accuracy of the returned range.
   * If the date-time cannot return the range, because the field is unsupported or for
   * some other reason, an exception will be thrown.
   * <p>
   * Note that the result only describes the minimum and maximum valid values
   * and it is important not to read too much into them. For example, there
   * could be values within the range that are invalid for the field.
   *
   * @param field the field to query the range for, not null
   * @return the range of valid values for the field, not null
   * @throws DateTimeException if the range for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported
   * @implSpec Implementations must check and handle all fields defined in {@link ChronoField}. If
   * the field is supported, then the range of the field must be returned. If unsupported, then an
   * {@code UnsupportedTemporalTypeException} must be thrown. <p> If the field is not a {@code
   * ChronoField}, then the result of this method is obtained by invoking {@code
   * TemporalField.rangeRefinedBy(TemporalAccessorl)} passing {@code this} as the argument. <p>
   * Implementations must ensure that no observable state is altered when this read-only method is
   * invoked. <p> The default implementation must behave equivalent to this code:
   * <pre>
   *  if (field instanceof ChronoField) {
   *    if (isSupported(field)) {
   *      return field.range();
   *    }
   *    throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
   *  }
   *  return field.rangeRefinedBy(this);
   * </pre>
   */
  default ValueRange range(TemporalField field) {
    if (field instanceof ChronoField) {
      if (isSupported(field)) {
        return field.range();
      }
      throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
    }
    Objects.requireNonNull(field, "field");
    return field.rangeRefinedBy(this);
  }

  /**
   * Gets the value of the specified field as an {@code int}.
   * <p>
   * This queries the date-time for the value of the specified field.
   * The returned value will always be within the valid range of values for the field.
   * If the date-time cannot return the value, because the field is unsupported or for
   * some other reason, an exception will be thrown.
   *
   * @param field the field to get, not null
   * @return the value for the field, within the valid range of values
   * @throws DateTimeException if a value for the field cannot be obtained or the value is outside
   * the range of valid values for the field
   * @throws UnsupportedTemporalTypeException if the field is not supported or the range of values
   * exceeds an {@code int}
   * @throws ArithmeticException if numeric overflow occurs
   * @implSpec Implementations must check and handle all fields defined in {@link ChronoField}. If
   * the field is supported and has an {@code int} range, then the value of the field must be
   * returned. If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. <p>
   * If the field is not a {@code ChronoField}, then the result of this method is obtained by
   * invoking {@code TemporalField.getFrom(TemporalAccessor)} passing {@code this} as the argument.
   * <p> Implementations must ensure that no observable state is altered when this read-only method
   * is invoked. <p> The default implementation must behave equivalent to this code:
   * <pre>
   *  if (range(field).isIntValue()) {
   *    return range(field).checkValidIntValue(getLong(field), field);
   *  }
   *  throw new UnsupportedTemporalTypeException("Invalid field " + field + " + for get() method,
   * use getLong() instead");
   * </pre>
   */
  default int get(TemporalField field) {
    ValueRange range = range(field);
    if (range.isIntValue() == false) {
      throw new UnsupportedTemporalTypeException(
          "Invalid field " + field + " for get() method, use getLong() instead");
    }
    long value = getLong(field);
    if (range.isValidValue(value) == false) {
      throw new DateTimeException(
          "Invalid value for " + field + " (valid values " + range + "): " + value);
    }
    return (int) value;
  }

  /**
   * Gets the value of the specified field as a {@code long}.
   * <p>
   * This queries the date-time for the value of the specified field.
   * The returned value may be outside the valid range of values for the field.
   * If the date-time cannot return the value, because the field is unsupported or for
   * some other reason, an exception will be thrown.
   *
   * @param field the field to get, not null
   * @return the value for the field
   * @throws DateTimeException if a value for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported
   * @throws ArithmeticException if numeric overflow occurs
   * @implSpec Implementations must check and handle all fields defined in {@link ChronoField}. If
   * the field is supported, then the value of the field must be returned. If unsupported, then an
   * {@code UnsupportedTemporalTypeException} must be thrown. <p> If the field is not a {@code
   * ChronoField}, then the result of this method is obtained by invoking {@code
   * TemporalField.getFrom(TemporalAccessor)} passing {@code this} as the argument. <p>
   * Implementations must ensure that no observable state is altered when this read-only method is
   * invoked.
   */
  long getLong(TemporalField field);

  /**
   * Queries this date-time.
   * <p>
   * This queries this date-time using the specified query strategy object.
   * <p>
   * Queries are a key tool for extracting information from date-times.
   * They exists to externalize the process of querying, permitting different
   * approaches, as per the strategy design pattern.
   * Examples might be a query that checks if the date is the day before February 29th
   * in a leap year, or calculates the number of days to your next birthday.
   * <p>
   * The most common query implementations are method references, such as
   * {@code LocalDate::from} and {@code ZoneId::from}.
   * Additional implementations are provided as static methods on {@link TemporalQuery}.
   *
   * @param <R> the type of the result
   * @param query the query to invoke, not null
   * @return the query result, null may be returned (defined by the query)
   * @throws DateTimeException if unable to query
   * @throws ArithmeticException if numeric overflow occurs
   * @implSpec The default implementation must behave equivalent to this code:
   * <pre>
   *  if (query == TemporalQueries.zoneId() ||
   *        query == TemporalQueries.chronology() || query == TemporalQueries.precision()) {
   *    return null;
   *  }
   *  return query.queryFrom(this);
   * </pre>
   * Future versions are permitted to add further queries to the if statement. <p> All classes
   * implementing this interface and overriding this method must call {@code
   * TemporalAccessor.super.query(query)}. JDK classes may avoid calling super if they provide
   * behavior equivalent to the default behaviour, however non-JDK classes may not utilize this
   * optimization and must call {@code super}. <p> If the implementation can supply a value for one
   * of the queries listed in the if statement of the default implementation, then it must do so.
   * For example, an application-defined {@code HourMin} class storing the hour and minute must
   * override this method as follows:
   * <pre>
   *  if (query == TemporalQueries.precision()) {
   *    return MINUTES;
   *  }
   *  return TemporalAccessor.super.query(query);
   * </pre>
   * <p> Implementations must ensure that no observable state is altered when this read-only method
   * is invoked.
   */
  default <R> R query(TemporalQuery<R> query) {
    if (query == TemporalQueries.zoneId()
        || query == TemporalQueries.chronology()
        || query == TemporalQueries.precision()) {
      return null;
    }
    return query.queryFrom(this);
  }

}
